Recombinant blood-coagulation proteases

ABSTRACT

The invention relates to a non-glycosylated protein with enzymatic and serin protease activity, the zymogenous form thereof comprising the following domains of a protease of the factor IX family: (a) a catalytic domain, N-terminal bonded with (b) a zymogenous activation domain, N terminal bonded with (c) a EGF1 and/or EGF2 domain. Said protein can be used in a same way as the natural serine proteases of the factor IX family.

The invention concerns truncated post-translationally non-modif ied blood plasma protease variants of the factor IX gene family (FVII, FIX, FX and protein C) composed of an EFG2 domain, activation peptide (AP) and catalytic domain (CD) as well as the process for their production by expression in a host cell, preferably in a microorganism, renaturation in vitro and subsequent activation with a suitable protease.

The blood plasma protease variants according to the invention are suitable for finding (screening) inhibitors, for the production of co-crystals composed of a protease variant and inhibitor for the purpose of X-ray structure analysis and drug modelling and as diagnostic test: components in activator tests.

Blood plasma proteases play a role in blood coagulation, wound closure by fibrin formation as well as in fibrinolysis i.e. clot dissolution in wound healing. After an injury the injury signal is amplified by the sequential activation (specific proteolysis) of inactive proenzymes to form active enzymes which initiates blood coagulation and ensures a rapid wound closure. Blood coagulation can be initiated by two paths, the intrinsic path in which all protein components are present in the blood and the extrinsic path in which a membrane protein, the so-called tissue factor plays a critical role.

The molecular mechanism of blood homeostasis (blood coagulation, fibrinolysis and the regulation of this equilibrium) and the components that are involved in this are comprehensively described in several review articles (Furie, B. and Furie, B. C., Cell 53 (1988) 505-518; Davie, E. W. et al., Biochem. 30 (1991) 10363-10379; Bergmeyer, H. U. (ed.): Methods of Enzymatic Analysis, Vol. V, chapter 3, 3rd ed., Academic Press, New York (1983)).

The proteases of the blood coagulation cascade are very complex proteins. As a rule they can only be isolated in a complicated manner from the natural raw material source, the blood plasma, in a limited amount, with varying quality, homogeneity and purity (Van Dam-Mieras, M. C. E. et al., In: Bergmeyer, H. U. (ed.), Methods of Enzymatic Analysis, Vol. V, 3rd ed., page 365-394, Academic Press, New York (1983)). They play an important role in the regulation of blood homeostasis which is the equilibrium between blood coagulation, clot formation and dissolution. This well-regulated system can become unbalanced by genetic defects such as haemophilia A (defective factor VIII) and haemophilia B (defective factor IX), as well as by acute disorders such as e.g. in cardiac infarction, embolism and stroke.

There is therefore a need for substances which can influence the system of blood coagulation and fibrinolysis according to the medical requirements. For example recombinantly produced factor VIII or factor IX or recently also factor VII are used to treat haemophilia A and B. tPA (tissue type plasminogen activator) and streptokinase (bacterial protease) are used for example for clot lysis e.g. after cardiac infarction. In addition to complex proteins, substances such as hirudin (peptide composed of 65 amino acids, specific thrombin inhibitor), heparin (heteroglycan, thrombin inhibition/cofactor) and vitamin K antagonists (inhibitors of γ-carboxylation; Glu residues of the Gla domain) are also used to inhibit blood coagulation. However, the available substances are often still very expensive (protein factors) and not ideal with regard to their medical application (side effects) so that there is a need for medicaments which can be used to specifically modulate blood coagulation and clot lysis.

The search for new modulators (activators, inhibitors) of blood coagulation, fibrinolysis and homeostasis can for example be carried out by screening substance libraries and subsequently improving an identified lead structure by drug modelling. For this it is necessary that the key protein(s) [target(s)] are available in an adequate amount and quality for screening and for crystallization investigations (e.g. improvement of the lead structure by the specific prediction of changes based on the 3D structure of the protein component and lead structure).

The activated serine proteases thrombin, FVIIa, FIXa, FXa, FXIa, FXIIa, kallikrein (blood coagulation), tPA, urokinase, plasmin (fibrinolysis) and activated protein C (regulatory anticoagulant) and inactive precursors (zymogens) thereof are for example attractive targets within homeostasis.

The isolation of inactive serine proteases (zymogens) from blood plasma and the subsequent activation by proteolysis is difficult, time-consuming, expensive and often does not yield the amount and quality that is for example desired for crystallization experiments. For example the plasma concentration of the inactive protease zymogens FX, FIX and FVII is only 10, 5 and 0.5 mg/l respectively (Furie, B. and Furie B. C., Cell 53 (1988) 505-518). Moreover the protease preparations isolated from the plasma and activated in vitro are often very heterogeneous and unstable. Furthermore non-uniform post-translational modifications (e.g. carbohydrate groups) impede the crystallization experiments.

Blood plasma proteases are complex glycoproteins that belong to the serine protease family. They are synthesized in the liver as inactive proenzymes (zymogens), secreted into the blood and are activated when required by specific proteolysis i.e. by cleavage of one or two peptide bonds. They are structurally very similar with regard to the arrangement of their protein domains and their composition (Furie, B. and Furie, B. C., Cell 53 (1988) 505-518).

According to Furie B. and Furie, B. C. the proteases of the factor IX family (factor VII, IX, X and protein C) are composed of

a propeptide,

a GLA domain,

an aromatic amino acid stack domain,

two EGF domains (EGF1 and EGF2),

a zymogen activation domain (activation peptide, AP) and

a catalytic protease domain (CD).

Furthermore the blood plasma proteases are post-translationally modified during secretion:

11-12 disulfide bridges

N- and/or O-glycosylation (GLA domain and activation peptide)

Bharadwaj, D. et al., J. Biol. Chem. 270 (1995) 6537-6542

Medved, L. V. et al., J. Biol. Chem. 270 (1995) 13652-13659

cleavage of the propeptide

γ-carboxylation of Glu residues (GLA domain)

β-hydroxylation of an Asp residue (EGF domains)

cleavage of the zymogen region (partially)

After activation of the zymogens (zymogenic form of the protein) by specific cleavage of one or two peptide bonds (activation peptide), the enzymatically active proteases are composed of two chains which, in accordance with their molecular weight, are referred to as the heavy and light chain. In the factor IX protease family the two chains are held together by an intermolecular disulfide bridge between the EGF2 domain and the protease domain. The zymogen-enzyme transformation (activation) leads to conformation changes within the protease domain. This enables an essential salt bridge necessary for the protease activity to form between the N-terminal amino acid of the prc)tease domain and an Asp residue within the protease domain. The N-terminal region is very critical for this subgroup of serine proteases and should not be modified. Only then is it possible for the typical active site of the serine proteases to form with the catalytic triad composed of Ser, Asp and His (Blow, D. M.: Acc. Chem. Res. 9 (1976) 145-152; Polgar, L.: In: Mechanisms of protease action. Boca Raton, Fla., CRC Press, chapter 3 (1989).

Blood plasma proteases can be produced in a classical manner by isolating the inactive zymogens from the blood and subsequently activating them or they can be produced recombinantly by expressing the corresponding cDNA in a suitable mammalian cell line or in yeast.

Production of Blood Plasma Proteases by Expression/secretion of the Zymogens or Active Proteases by Means of Eukaryotic Host/vector Systems

FVII: Hagen, F. S. et al., EPS 0200421; Pedersen, A. H. et al., Biochem. 28 (1989) 9391-9336; FIX: Lin, S.-W. et al., J. Biol. Chem. 265 (1990) 144-150; FX: Wolf, D. L. et al., J. Biol. Chem. 266 (1991) 13726-13730; Protein C: Bang, N. U. et al., EPS 0191606.

As a rule host cells are used which are able to post-translationally modify the blood plasma proteases like the native enzyme during the secretion process. The zymogen-enzyme transformation is then carried out subsequently during the downstream processing e.g. by using an activator from snake venom in the case of prothrombin or factor X (Sheehan, J. P. et al., J. Biol. Chem. 268 (1993) 3639-3645; Fujikawa, K. et al. Biochem. 11 (1972) 4892-4898).

For the purpose of zymogen-enzyme activation in vivo (already during secretion), the natural zymogen cleavage sites or the entire activation peptide were substituted by protease cleavage sites (several adjacent basic amino acids) which can be cleaved by specifically cleaving proteases that occur naturally in the secretion path of the host cell such as e.g. Kex2 (yeast) or PACE (mammalian cell lines). (FX: Wolf, D. L. et al., J. Biol. Chem. 266 (1991) 13726-13730; Prothrombin: Holly, R. D. and Foster, D. C., WO 93/13208).

The production or protease variants (FX: Rezaie, A. R: et al., J. Biol. Chem. 268 (1993) 8176-8180); FIX: Zhong, D. G. et al., Proc. Natl. Acad. Sci. USA 91 (1994) 3574-3578), mutants (FX: Rezaie, A. R. et al., J. Biol. Chem. 269 (1994) 21495-21499; Thrombin: Yee, J. et al., J. Biol. Chem. 269 (1994) 17965-17970); FVII: Nicolaisen, E. M. et al., WO 88/10295) and chimeras e.g. composed as FIX and FX (Lin, S.-W. et al., J. Biol. Chem. 265 (1990) 144-150; Hertzberg, M. S. et al., J Biol. Chem. 267 (1992) 14759-14766) by means of eukaryotic host/vector systems is also known.

Disadvantages of Expression in Eukaryotic Mammalian Cell Lines:

time-consuming

limited with regard to expression output

expensive

post-translational modifications

Production of Blood Plasma Proteases by Expression in Prokaryotes and Subsequent Renaturation of the Expression Product

Thogersen, H. C. et al. (WO 94/18227) describe the renaturation of FX variants my means of a cyclic renaturation process in which the inactive FX protein is immobilized in a chromatographic column by means of a metal chelate complex (poly(His)-affinity handle).

A fusion protein is used for this composed of a truncated FX variant (EGF1, EGF2 and protease domain), an additional FXa protease recognition sequence and an attachment aid at the C-terminus of the catalytic domain composed of 6 histidine residues.

Disadvantages:

A fusion protein composed of protease and poly-his attachment aid must be constructed.

The renaturation process is very complicated.

many renaturation cycles are necessary

complex apparatus

the yield is only 10%

The attachment aid may have to be removed after the renaturation.

The autocatalysis only removes the poly-His tail but not the additionally introduced FXa cleavage site.

DiBella, E. E. et al. (J. Biol. Chem. 270 (1995) 163-169) describe the renaturation of a truncated thrombin variant (prethrombin-2) composed of an A chain (49 amino acids) and a B chain (295 amino acids).

However, an analogous factor Xa variant composed of the activation peptide and protease domain (see example 4) cannot be renatured. The EFG2 domain is necessary in addition to the zymogen region (activation peptide composed of ca. 50 amino acids) for FXa renaturation. This also applies to all members of the FIX protein family (FVII, FIX, FX and protein C).

Thrombin is not a member of the FIX gene family and has two kringle domains instead of two EGF domains.

It was surprisingly found that enzymatically active proteins with serine protease activity can be produced by expression of a corresponding DNA in prokaryotes, renaturation of the expression product and enzymatic cleavage if they are composed of a serine protease domain (catalytic domain), N-terminally linked to a zymogen activation domain and an EGF domain (EGF1 and/or EGF2).

The specificity of the active and truncated serine proteases according to the invention of the factor IX family are unchanged (identical) and consequently they can be used in activity tests as well as to screen for new modulators (activators, inhibitors).

It was not possible to produce an enzymatically active protease domain by expression of a DNA coding only for the catalytic domain and renaturation of the inactive expression product.

The desired enzymatically active protease domains of e.g. FIXa and FXa could also not be produced by N-terminal protease domain fusion proteins with a selective protease cleavage site (e.g. enterokinase cleavage site). It was not possible to renature the expression products according to the prior art.

The invention concerns a non-glycosylated, enzymatically active protein with serine protease activity and its zyomogenic precursor form composed of the following domains of a protease from the factor IX family:

a) the catalytic domain, N-terminally linked with

b) a zymogen activation domain (activation peptide), N-terminally linked with

c) an EGF1 and/or EGF2 domain preferably EGF2 or EGF1 and EGF2).

The zymogen activation domain is preferably composed of an oligopeptide with up to 50 amino acids. After cleavage of the inventive zymogenic (inactive) one chain form in the zymogen activation domain, a two chain active protease is formed. In the two chain form the two chains are linked by an intermolecular disulfide bridge (interchain) (FIG. 1 and FIG. 2).

The proteins according to the invention are preferably composed of the EGF2 domain, the zymogen activation domain and the catalytic domain of factor X and/or factor IX. A protein is also preferred which is composed of the EGF2 domain and the catalytic domain of factor X as well as the activation peptide of factor IX. A protein is particularly preferred which is composed of the N-terminal part of the factor X EGF2 domain (amino acid position 108-154, FIG. 3), the C-terminal part of the factor IX EGF2-domain, the factor IX activation peptide and the factor IX N-terminal half-side (amino acid position 133-289, FIG. 4) and the factor X C-terminal half-side (amino acid position 322-454, FIG. 3).

The zymogens and active proteases of the factor IX family according to the invention can be used instead of the natural zymogens and proteases. Advantageous applications are for example the use as a restriction protease (preferably factor Xa) in biotechnology, as a component of an enzymatic method of determination in diagnostics especially for the indirect determination of blood coagulation protease activities (preferably factor IXa determination). A further application is as a target in screening assays to search for modulators (activators, inhibitors) of blood coagulation, fibrinolysis or homeostasis. Finally the proteins according to the invention provide serine proteases that can be crystallized which can be advantageously used for crystallization investigations (preferably co-crystallization with activators and inhibitors).

The active proteases of the factor IX family (factor IXa, factor Xa, factor VIIa and protein C) according to the invention are particularly preferably used to identify inhibitors. In this case the direct determination of factor IXa and the identification of factor IXa inhibitors is especially preferred. Furthermore the zymogens according to the invention can be used as ingredients in a diagnostic test. In this case the zymogen according to the invention (e.g. factor X) is activated by the protease to be determined (e.g. factor IXa). The activated zymogen (e.g. factor Xa) then cleaves a chromogenic peptide Substrate (e.g. Chromozym X) and generates a measurement signal (e.g. p-nitroaniline). The colour change that occurs is a measure of the concentration of factor IXa in the sample and is proportional to the protease activity to be determined.

A spacer with up to 50 amino acids is preferably inserted between the zymogen activation domain and the EGF domain (or the EGF domains). When the zymogenic one chain form according to the invention is cleaved in the zymogen activation domain, an active protein is obtained in a two chain form. Both chains are linked by an intermolecular disulfide bridge in the two chain form (FIG. 1 and FIG. 2).

The proteins according to the invention are preferably composed of the EGF2 domain, the activation peptide and the catalytic domain of factor X and/or factor IX. A protein is also preferred which is composed of the EGF2 domain and the catalytic domain of factor X as well as the activation domain of factor IX.

Methods

Recombinant DNA Technique

Standard methods were used to manipulate DNA as described in Sambrook, J. et al. (1989) In: Molecular cloning: A laboratory manual. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. The molecular biological reagents were used according to the manufacturer's instructions.

Protein Determination

The protein concentration of the protease variants was determined by determining the optical density (OD) at 280 nm using the molar extinction coefficients calculated on the basis of the amino acid sequence.

Expression Vector

The vector for the expression of the blood coagulation protease variants is based on the expression vector pSAM-CORE for core-streptavidin. The preparation and description of the plasmid p-SAM-CORE is described. by Kopetzki, E. et al., in WO 93/09144.

The core-streptavidin gene was replaced by the desired protease variant gene in the pSSM-CORE vector.

The following examples, publications, the sequence protocol and the figures further elucidate the invention, the protective scope of which results from the patent claims. The described methods are to be understood as examples which also still describe the subject matter of the invention even after modifications.

DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram of the blood plasma proteases of the FIX protease family.

FIG. 2 is a diagram of the constructed truncated FIX, FX and FIX/X chimeric blood plasma proteases. (In the case of rFIX/X-EGF2-AP-CD the factor X part is white and the factor IX part is black) Abbreviations: AP=activation peptide; AA=aromatic amino acid stack domain; CD=catalytic domain; EGF1=epidermal growth factor-like domain 1; EGF2=epidermal growth factor-like domain 2; GLA=γ-carboxyglutamic acid-rich domain.

FIG. 3 shows the nucleotide and amino acid sequence for FX given in Kaul, R. K. et al. (Gene 41 (1986) 311-314) (the nucleotide sequence is shown in SEQ ID NO:15).

FIG. 4 shows the nucleotide and amino acid sequence for FIX given in McGraw, R. A. et al. (Proc. Natl. Acad. Sci. USA 82 (1985) 2847-2851) (the nucleotide sequence is shown in SEQ ID NO:16).

EXAMPLE 1 Cloning the Catalytic Domain of the FX Protease Gene

(Plasmid: pFX-CD)

The FX cDNA from bp position 649 to 1362, coding for the FX protease domain from amino acid position 217 to 454 (cDNA sequence acid sequence and amino acid sequence numbering according to the publication of Kaul, R. K. et al., (Gene 41 (1986) 311-314; FIG. 3) was amplified in a polymerase chain reaction (PCR) according to the method of Mullis, K. B. and Faloona, F. A., (Methods Enzymol. 155, (1987) 350-355) using the PCR primers N1 (SEQ ID NO:1) and N2 (SEQ ID NO:2).

             EcoRI BspHI N1: 5′-AAAAAAGAATTC TC ATG ATCGTGGGAGGCCAGGAATGCAAG-3′                      MetIleValGlyGlyGlnGluCysLys              HindIII N2: 5′-AAAAAAAAGCTTCATTACTTGGCCTTGGGCAAGCCCCTGGT-3′

and a commercially available human liver cDNA gene bank (vector: Lambda ZAP® II) from the Stratagene Company (La Jolla, Calif., U.S.A.) as template DNA. The PCR primers introduced a singular BspHI cleavage site and an ATG start codon at the 5′ end of the coding region and a singular HindIII cleavage site at the 3′ end of the coding region.

The ca. 740 bp long PCR product was digested with the restriction endonucleases BspHI and HindIII and the ca. 725 bp long BspHI/HindIII-FX fragment was ligated into the ca. 2.55 kbp long NcoI/HindIII-pSAM-CORE vector fragment after purification by agarose gel electrophoresis. The desired plasmid pFX-CD was identified by restriction mapping and the FX cDNA sequence isolated by PCR was checked by DNA sequencing.

EXAMPLE 2 Construction of the FX Protease Gene with an N-terminal (His)₄ Tail, Enterokinase Cleavage Site and Catalytic Domain (plasmid: pFX-EK-CD)

The reading frame of the cloned FX-CD gene (see example 1) was linked at the 5′ end with a nucleotide sequence which codes for the amino acid sequence MHHHHDDDDK (SEQ ID NO:17) and contains the ATG start codon, a poly-His sequence and an enterokinase cleavage site. The singular BsmI cleavage site located at the 5′ end of the FX-CD gene and the neighbouring singular EcoRI cleavage site that is upstream in the promoter were used to construct this FX-EK-CD variant gene.

For this the plasmid pFX-CD was digested with the restriction endonucleases EcoRI and BsmI and the ca. 3.25 kbp long EcoRI/BsmI-pFX-CD vector fragment was ligated with the FX-EK-CD DNA adaptor after isolation by means of agarose gel electrophoresis. The FX-EK-CD adaptor was constructed by hybridization from the complementary oligonucleotides N3 (SEQ ID NO:3) and N4 (SEQ ID NO:4) (reaction buffer: 12.5 mmol/l Tris-HCl, pH 7.0 and 12.5 mmol/l MgCl₂; N concentration: 1 pmol/60 μl each time).

FX-EK-CD Adaptor

N3: 5′-AATTCATTAAAGAGGAGAAATTAAAATGCATCACCACCACGACGATGACGACAAGATCGTGGGAGGCCAGGAATGCA-3′ N4: 5′-CATTCCTGGCCTCCCACGATCTTGTCGTCATCGTCGTGGTGGTGATGCATTTTAATTTCTCCTCTTTAATG-3′        EcoRI                                                                  BsmI N3: 5′-AATTCATTAAAGAGGAGAAATTAAAATGCATCACCACCACGACGATGACGACAAGATCGTGGGAGGCCAGGAATGCA-3 N4: 3′-    GTAATTTCTCCTCTTTAATTTTACGTAGTGGTGGTGCTGCTACTGCTGTTCTAGCACCCTCCGGTCCTTAC -5′                                 MetHisHisHisHisAspAspAspAspLysIleValGlyGlyGlnGluCys

EXAMPLE 3 Cloning of the FX Protease Gene with an EGF2 Domain, Activation Peptide and Catalytic Domain (plasmid: pFX-EGF2-AP-CD)

The FX cDNA from bp position 322 to 1362, coding for the EGF2 domain, the activation peptide and the catalytic protease domain from amino acid position 108 to 454 (cDNA sequence acid sequence and amino acid sequence numbering according to FIG. 3) was amplified by means of PCR using the PCR primers N5 (SEQ ID NO:5) and N2 (SEQ ID NO:2).

               EcoRI N5: 5′-AAAAAAGAATTCATTAAAGAGGAGAAATTAAAATGCGGAAGCTCTGCAGCCTGGACAAC-3′                                        MetArgLysLeuCysSerLeuAspAsn

and a commercially available human liver cDNA gene bank (vector: Lambda ZAP® II) from the Stratagene Company (La Jolla, Calif., U.S.A.) as template DNA. The PCR primers introduced an ATG start codon and a singular EcoRI cleavage site at the 5′ end of the coding region and a singular HindIII cleavage site at the 3′ end of the coding region.

The ca. 1.09 kbp long PCR product was digested with the restriction endonucleases EcoRI and BstEII and the ca. 1.02 kbp long EcoRI/BstEII-FX fragment was ligated into the ca. 2.58 kbp long EcoRI/BstEII-pFX-CD vector fragment (example 1) after purification by agarose gel electrophoresis. The desired plasmid pFX-EGF2-AP-CD was identified by restriction mapping and the FX cDNA sequence isolated by PCR was checked by DNA sequencing.

EXAMPLE 4 Construction of the FX Protease Gene with Truncated EGF2 Domain, Activation Peptide and Catalytic Domain (plasmid: pFX-ΔEGF2-AP-CD)

The FX cDNA from bp position 460 to 1362, coding for a truncated EGF2 domain, the activation peptide and the catalytic protease domain from amino acid position 154 to 454 (cDNA sequence acid sequence and amino acid sequence numbering according to FIG. 3) was amplified by means of PCR using the PCR primers N6 (SEQ ID NO:6) and N2 (SEQ ID NO:2).

              EcoRI N6: 5′-AAAAAAGAATTCATTAAAGAGGAGAAATTAAAATGTGcGGtAAACAGACCCTGGAACG-3′                                       MetCysGlyLysGlnThrLeuGlu

and the plasmid pFX-EGF2-AP-CD (example 3) as template DNA. In the PCR the 5′ region of the structural gene (amino acid positions 2 and 3) was adapted to the codons preferably used in E. coli without changing the protein sequence by means of the N6 primer (ATG environment with optimized codon usage, indicated by the bases written in small letters in the N6 primer).

The ca. 960 bp long PCR product was digested with the restriction endonucleases EcoRI and HindIII and the ca. 950 bp long EcoRI/HindIII-FX fragment was ligated into the ca. 2.53 kbp long EcoRI/HindIII-pSAM-CORE vector fragment (example 1) after purification by agarose gel electrophoresis. The desired plasmid pFX-ΔEGF2-AP-CD was identified by restriction mapping and the FX DNA sequence amplified by PCR was checked by DNA sequencing.

EXAMPLE 5 Construction of the FX Protease Gene with Activation Peptide and Catalytic Domain (plasmid: pFX-AP-CD)

The FX cDNA from bp position 496 to 1362, coding for the activation peptide and the catalytic protease domain from amino acid position 166 to 454 (cDNA sequence and amino acid sequence numbering according to FIG. 3) was amplified by means of PCR using the PCR primers N7 (SEQ ID NO:7) and N2 (SEQ ID NO:2).

              NcoI N7: 5′-AAAAAACCATGGTtGCtCAGGCtACCAGCAGCAGC-3′                MetValAlaGlnAlaThrSerSerSer

and the plasmid pFX-EGF2-AP-CD (example 3) as template DNA. The 5′ region of the structural gene (amino acid positions 2, 3 and 5) were adapted to the cc)dons preferably used in E. coli without changing the protein sequence by means of the N7 primer (ATG environment with optimized codon usage, indicated by the bases written in small letters in the N7 primer).

The ca. 890 bp long PCR product was digested with the restriction endonucleases NcoI and HindIII and the ca. 880 bp long NcoI/HindIII-FX fragment was ligated into the ca. 2.55 kbp long NcoI/HindIII-pSAM-CORE vector fragment (example 1) after purification by agarose gel electrophoresis. The desired plasmid pFX-AP-CD was identified by restriction mapping and the FX DNA sequence amplified by PCR was checked by DNA sequencing.

EXAMPLE 6 Cloning of the Catalytic Domain of the FIX Protease Gene (plasmid: pFIX-CD)

The FIX cDNA from bp position 690 to 1403, coding for the FIX protease domain from amino acid position 181 to 415 (cDNA sequence and amino acid sequence numbering according the publication of McGraw, R. A. et al. (Proc. Natl. Acad. Sci. USA 82 (1985) 2847-2851; FIG. 4) was amplified using the PCR primers N8 (SEQ ID NO:8) and N9 (SEQ ID NO:9).

              NcoI N8: 5′-AAAAAACCATGGTTGTTGGTGGAGAAGATGCCAAACC-3′                MetValValGlyGlyGluAspAlaLys              HindIII N9: 5′-AAAAAAAAGCTTCATTAAGTGAGCTTTGTTTTTTCCTTAATC-3

and a commercially available human liver cDNA gene bank (vector: Lambda ZAP® II) from the Stratagene Company (La Jolla, Calif., U.S.A.) as template DNA. The PCR primers introduced a singular NcoI cleavage site and an ATG start codon at the 5′ end of the coding region and a singular HindIII cleavage site at the 3′ end of the coding region.

The ca. 730 bp long PCR product was digested with the restriction endonucleases NcoI and HindIII and the ca. 720 bp long NcoI/HindIII-FIX fragment was ligated into the ca. 2.55 kbp long NcoI/HindIII-pSAM-CORE vector fragment (example 1) after purification by agarose gel electrophoresis. The desired plasmid PFIX-CD was identified by restriction mapping and the FIX cDNA sequence isolated by PCR was checked by DNA sequencing.

EXMAPLE 7 Construction of the FIX Protease Gene with EGF2 Domain, Activation Peptide and Catalytic Domain (plasmid: pFIX-EGF2-AP-CD)

The FIX cDNA from bp position 402 to 986, coding for the EGF2 domain, the activation peptide and the N-terminal region of the FIXa protease domain from amino acid position 85 to 278 (cDNA sequence and amino acid sequence numbering according to FIG. 4) was amplified using the PCR primers N10 (SEQ ID NO:10) and N11 (SEQ ID NO:11).

               NcoI N10: 5′-AAAAAACCATGGATGTAACATGTAACATTAAGAATGGCA-3′                 MetAspValThrCysAsnIleLysAsnGly N11: 5′-GGGTTCGTCCAGTTCCAGAAGGGC-3′

and a commercially available human liver cDNA gene bank (vector: Lambda ZAP® II) from the Stratagene Company (La Jolla, Calif., U.S.A.) as template DNA. The PCR primer N10 introduced an ATG start codon at the 5′ end of the coding region and a singular NcoI cleavage site.

The ca. 590 bp long PCR product was digested with the restriction endonucleases NcoI and BsmI and the ca. 360 bp long NcoI/BsmI-FIX-EGF2-AP fragment wats ligated into the ca. 3.2 kbp long NcoI/BsmI-pFIX-CD vector fragment (example 6) after purification by agarose gel electrophoresis. The desired plasmid pFIX-EGF2-AP-CD was identified by restriction mapping and the FIX cDNA sequence amplified by PCR was checked by DNA sequencing.

EXAMPLE 8

Construction of a Chimeric Protease Gene Composed of FIX and FX (plasmid: pFIX/X-EGF2-AP-CD)

The chimeric FIX/FX protease gene was composed of the N-terminal part of the FX EGF2 domain (bp position: 322-462; amino acid position: 108-154, FIG. 3), the C-terminal part of the FIX EGF2, the FIX activation peptide and the FIX N-terminal half-side (bp position: 397-867; amino acid position: 133-289; FIG. 4) and the FX C-terminal half-side (bp position: 964-1362; amino acid position: 322-454; FIG. 3).

For this the DNA coding for the C-terminal part of the FIX EGF2, the FIX activation peptide and the FIX N-terminal half-side from bp position 397 to 867 (amino acid position: 133-289; FIG. 4) was amplified in a first PCR reaction using the PCR primers N12 (SEQ ID NO:12) and N13 (SEQ ID NO:13).

               StuI N12: 5′-AAAAAAAGGCCTGCATTCCCACAGGGCCCTACCCCTGTGGAAGAGTTTCTGTTTCACAAAC-3′                                               GlyArgValSerValSerGln--                                               |133 FIX-EGF2 ->                MroI N13: 5′-AAAAAAtCCgGAAGGCAAATAGGTGTAACGTAGCTGTTTAGC-3′

and the plasmid pFIX-EGF2-AP-CD (example 7) as template DNA. The FX-EGF2 DNA sequence was linked with the FIX-EGF2 DNA sequence by means of the 5′ overhanging nucleotide sequence of the PCR primer N12. It is composed of the FX DNA sequence from bp position 430 to 462 (FIG. 3) with a singular StuI cleavage site at the 5′ end. The FIX DNA was linked with the FX DNA using the 5′ overhanging nucleotide sequence of the N13 primer. It is composed of the FX DNA sequence from bp position: 964-970 (FIG. 3). A singular MroI cleavage site was produced in this sequence by two base pair substitutions (indicated by the bases written in small letters in the N13 primer) without changing the protein sequence. The FX C-terminal half-side from bp position: 964-1362 (amino acid position: 322-454; FIG. 3) was amplified in a second PCR reaction using the PCR primers N14 (SEQ ID NO:14) and N2 (SEQ ID NO:2).

                          MroI N14: 5′AAAAAAtCCgGAGCGTGACTGGGCCGAGTCC-3

and the plasmid pFX-EGF2-AP-CD (example 3) as template DNA. A singular MroI cleavage site was introduced by means of the N14 primer at the 5′ end within the coding FX-CD region by two bp substitutions (indicated by the bases written in small letters in the N14 primer) without changing the amino acid sequence.

The first PCR product was digested with StuI and MroI and the second PCR product was digested with MroI and HindIII. Afterwards the ca. 510 bp long StuI/MroI fragment was ligated with the ca. 400 bp long MroI/HindIII fragment and the ca. 2640 bp long StuI/HindIII-pFX-EGF2-AP-CD vector fragment (example 3) in a three fragment ligation. The desired plasmid pFIX/X-EGF2-AP-CD was identified by restriction mapping and the FIX/X DNA sequence amplified by PCR was checked by DNA sequencing.

EXAMPLE 9

a) Expression of the Protease Gene in E. coli

In order to express the protease gene, the E. coli K12 strain UT5600 (Grodberg, J. and Dunn, J. J. J. Bacteriol. 170 (1988) 1245-1253) was transformed in each case with one of the expression plasmids pFX-CD, pFX-EK-CD, pFX-EGF2-AP-CD, pFX-ΔEGF2-AP-CD, pFX-AP-CD, pFIX-CD, pFIX-EGF2-AP-CD and pFIX/X-EGF2-AP-CD (ampicillin resistance) described in examples 1-8 and with the lacIq repressor plasmid pUBS520 (kanamycin resistance, preparation and description see: Brinkmann, U. et al., Gene 85 (1989) 109-114).

The UT5600/pUBS520/cells transformed with the expression plasmids pFX-CD, pFX-EK-CD, pFX-EGF2-AP-CD, pFX-ΔEGF2-AP-CD, pFX-AP-CD, pFIX-CD, pFIX-EGF2-AP-CD and pFIX/X-EGF2-AP-CD were cultured in a shaking culture in DYT medium (1% (w/v) yeast extract, 1% (w/v) Bacto Tryptone, Difco and 5% NaCl) containing 50-100 mg/l ampicillin and 50 mg/l kanamycin at 37° C. up to an optical density at 550 nm (OD₅₅₀) of 0.6-0.9 and subsequently induced with IPTG (final concentration 1-5 mmol/l). After an induction phase of 4-8 hours (h) at 37° C., the cells were harvested by centrifugation (Sorvall RC-5B centrifuge, GS3 rotor, 6000 rpm, 15 min), washed with 50 mmol/l Tris-HCl buffer pH 7.2 and stored at −20° C. until further processing. The cell yield from a 1 l shaking culture was 4-5 g (wet weight).

b) Expression Analysis

The expression of the UT5600/pUBS520/cells transformed with the plasmids pFX-CD, pFX-EK-CD, pFX-EGF2-AP-CD, pFX-ΔEGF2-AP-CD, pFX-AP-CD, pFIX-CD, pFIX-EGF2-AP-CD and pFIX/X-EGF2-AP-CD was analysed. For this purpose cell pellets from in each case 1 ml centrifuged culture medium were resuspended in 0.25 ml 10 mmol/l Tris-HCl, pH 7.2 and the cells were lysed by ultrasonic treatment (2 pulses of 30 s at 50% intensity) using a Sonifier® Cell Disruptor B15 from the Branson Company (Heusenstamm, Germany). The insoluble cell components were sedimented (Eppendorf 5415 centrifuge, 14000 rpm, 5 min) and ⅕ volumes (vol) 5×SDS sample buffer (1×SDS sample buffer: 50 mmol/l Tris-HCl, pH 6.8, 1% SDS, 1% mercaptoethanol, 10% glycerol, 0.001% bromophenol blue) was added to the supernatant. The insoluble cell debris fraction (pellet) was resuspended in 0.3 ml 1×SDS sample buffer containing 6-8 M urea, the samples were incubated for 5 min at 95° C. and centrifuged again. Afterwards the proteins were separated by SDS polyacrylamide gel electrophoresis (PAGE) (Laemmli, U. K., Nature 227 (1970) 680-685) and stained with Coomassie Brilliant Blue R dye.

The protease variants synthesized in E. coli were homogeneous and were exclusively found in the insoluble cell debris fraction (inclusion bodies, IBs). The expression yield was 10-50% relative to the total E. coli protein.

EXAMPLE 10 Cell Lysis, Solubilization and Renaturation of the Protease Variants

a) Cell Lysis and Preparation of Inclusion Bodies (IBs)

The cell pellet from 3 l shaking culture (ca. 15 g wet weight) was resuspended in 75 ml 50 mmol/l Tris-HC1, pH 7.2. The suspension was admixed with 0.25 mg/ml lysozyme and it was incubated for 30 min at 0° C. After addition of 2 mmol/l MgCl₂ and 10 μg/ml DNase I (Boehringer Mannhein GmbH, catalogue No. 104159) the cells were disrupted mechanically by means of high pressure dispersion in a French® Press from the SLM Amico Company (Urbana, Ill., USA). Subsequently the DNA was digested for 30 min at room temperature (RT). 37.5 ml 50 mmol/l Tris-HCl pH 7.2, 60 mmol/l EDTA, 1.5 mol/l NaCl, 6% Triton X-100 was added to the preparation, it was incubated for a further 30 min at RT and centrifuged in a Sorvall RC-5B centrifuge (GSA Rotor, 12000 rpm, 15 min). The supernatant was discarded, 100 ml 50 mmol/l Tris-HCl, pH 7.2, 20 mmol/l EDTA was added to the pellet, it was incubated for 30 min while stirring at 4° C. and again sedimented. The last wash step was repeated. The purified IBs (1.5-2.0 g wet weight, 25-30% dry mass, 100-150 mg protease) were stored at −20° C. until further processing.

b) Solubilization and Derivatization of the IBs

The purified IBs were dissolved within 1 to 3 hours at room temperature while stirring at a concentration of 100 mg IB pellet (wet weight)/ml corresponding to 5-10 mg/ml protein in 6 mol/l guanidinium-HCl, 100 mmol/l Tris-HCl, 20 mmol/l EDTA, 150 mmol/l GSSG and 15 mmol/l GSH, pH 8.0. Afterwards the pH was adjusted to pH 5.0 and the insoluble components were separated by centrifugation (Sorvall RC-5B centrifuge, SS34 rotor, 16000 rpm, 10 min). The supernatant was dialysed for 24 hours at 4° C. against 100 vol. 4-6 mol/l guanidinium-HCl pH 5.0.

c) Renaturation

The renaturation of the protease variants solubilized in 6 mol/l guanidinium-HCl and derivatized with GSSG/GSH was carried out at 4° C. by repeated (e.g. 3-fold) addition of 0.5 ml IB solubilisate/derivative in each case to 50 ml 50 mmol/l Tris-HCl, 0.5 mol/l arginine, 20 mmol/l CaCl₂, 1 mmol/l EDTA and 0.5 mmol/l cysteine, pH 8.5 at intervals of 24 hours and subsequent incubation for 48 hours at 4° C. After completion of the renaturation reaction the insoluble components were separated by filtration with a filtration apparatus from the Satorius Company (Göttingen, Germany) equipped with a deep bed filter K 250 from the Seitz Company (Bad Kreuznach, Germany).

d) Concentration and Dialysis of the Renaturation Preparations

The clear supernatant containing protease was concentrated 10-15-fold by cross-flow filtration in a Minisette (membrane type: Omega 10K) from the Filtron Company (Karlstein, Germany) and dialysed for 24 hours at 4° C. against 100 vol. 20 mmol/l Tris-HCl and 50 mmol/l NaCl, pH 7.2 to remove guanidinium-HCl and arginine. Precipitated protein was removed by centrifugation (Sorvall RC-5B centrifuge, SS34 rotor, 16000 rpm, 20 min) and the clear supernatant was filtered with a Nalgene® disposable filtration unit (pore diameter: 0.2 μm) from the Nalge Company (Rochester, N.Y., USA).

e) Determination of the Renaturation Efficiency

The protein concentration of the renatured, concentrated and filtered renaturation preparations was determined by measuring the optical density (OD) at 280 nm using the molar extinction coefficients calculated on the basis of the amino acid sequences for rFX-CD, rFX-EK-CD, rFX-EGF2-AP-CD, rFX-ΔEGF2-AP-CD, rFX-AP-CD, rFIX-CD, rFIX-EGF2-AP-CD and rFIX/X-EGF2-AP-CD

A sample of the renaturation preparations composed of natively folded protease and falsely disulfide-bridged protease oligomers was separated by non-reducing SDS PAGE (example 13b). The desired soluble monomeric protease zymogens were identified by means of the apparent molecular weight and the band strength. The renaturation efficiency was estimated from the comparison (ratio) of the band intensities of monomeric protease zymogens to the remaining bands (protein smear).

molar extinction molecular renaturation coefficient weight efficiency Protease variant [cm² mol⁻¹] [kDa] [%] rFX-CD 33540 27.3 <0.1 rFX-EK-CD 33540 28.4 <0.1 rFX-EGF2-AP-CD 43490 39.3  5-10 rFX-ΔEGF2-AP-CD 40570 34.3 <0.1 rFX-AP-CD 40510 32.9 <0.1 rFIX-CD 41670 26.3 <0.1 rFIX-EGF2-AP-CD 44650 36.9 15-20 rFIX/X-EGF2-AP-CD 43370 37.5 10-15

Result

It was only possible to renature the protease variants with an EGF2 domain, the activation peptide (AP) and catalytic domain (CD).

EXAMPLE 11 Purification of the Renatured Inactivated Protease Variants

The inactive protease variants from the renaturation preparations can, if required, be further purified with chromatographic methods which are known to a person skilled in the art.

a) Purification of the Protease Variants by Ion Exchange Chromatography on Q-Sepharose-ff

The concentrated renaturation preparation that had been dialysed against 20 mmol/l Tris-HCl and 50 mmol/l NaCl, pH 8.0 was applied to a Q-Sepharose ff column (1.5×11 cm, V=20 ml; loading capacity: 10 mg protein/ml gel) from the Pharmacia Biotech Company (Freiburg, Germany) (2 column volumes/hour, 2 CV/h) equilibrated with the same buffer and it was washed with the equilibration buffer until the absorbance of the eluate at 280 nm had reached the blank value of the buffer. The bound material was eluted by a gradient of 50-500 mmol/l NaCl in 20 mmol/l Tris-HCl, pH 8.0 (2 CV/h). The proteases were eluted at an NaCl concentration of 100-150 mmol/l. The fractions containing protease were identified by non-reducing and reducing SDS PAGE and the elution peak was pooled.

b) Final Purification of the Inactive Protease Variants by Ion Exchange Chromatography on Heparin-Sepharose CL-6B

After chromatography on a Q-Sepharose ff column, the combined fractions containing protease were directly applied (2 CV/h) to a heparin-Sepharose CL-6B column (1.5×11 cm, V=20 ml, loading capacity: 1 mg protein/mL gel) from the Pharmacia Biotech Company (Freiburg, GFR) that had been equilibrated with 20 mmol/l Tris-HCl and 200 mmol/l NaCl, pH 8.0. Afterwards it was washed with equilibration buffer until the absorbance of the eluate at 280 nm reached the blank value for the buffer. The bound material was eluted by a gradient of 0.2-1.0 mol/l NaCl in 20 mmol/l Tris-HCl, pH 8.0 (2 CV/h). The proteases were eluted at a NaCl concentration of 500-600 mmol/l. The fractions containing protease were identified by non-reducing and reducing SDS PAGE, the elution peak was combined and dialysed against 20 mmol/l Tris-HCl, 50-200 mmol/l NaCl, 5 mmol/l CaCl₂, pH 7.8.

EXAMPLE 12 Activation and Purification of the Activated Protease Variants

The renatured purified inactive rFIX and rFX protease variants were activated with purified Russel's viper venom (RVV-X) protease. The RVV-X protease was, as described in the publication by Esmon, C. T. (prothrombin activation, doctoral dissertation, Washington University, St. Louis, Mo. (1973)), purified from the commercially available snake venom lyophilisate from the Sigma Aldrich Chemie GmbH Co. (Deisenhofen, GFR) by gel filtration followed by ion exchange chromatography on Q-Sepharose ff.

a) Activation and Purification of rFIX-EGF2-AP-CD Protease Variant with RVV-X

The protease variant rFIX-EGF2-AP-CD was digested at 25° C. at a concentration of 0.5 to 2.0 mg/ml and a protease/substrate ratio of 1:10 to 1:20 in 20 mmol/l Tris-HCl, 50 mmol/l NaCl, 10 mmol/l CaCl₂, pH 7.8. The time course of the enzymatic FIX activation was monitored by determining the activity with a chromogenic substrate (see example 13a) until the digestion was completed (plateau, maximum activation). For this purpose samples (10 to 100 μl) were taken from the reaction preparation at intervals of 3-4 h over a period of up to 24 hours and the generated rFIXa activity was determined. After reaching the activation plateau, the RVV-X digest was purified by negative chromatography on Q-Sepharose-ff.

RVV-X and non-activated rFIX-EGF2-AP-CD protease bind under the given conditions to Q-Sepharose-ff, but rFIXa-EGF2-AP-CD protease does not.

The digestion preparation was applied (2 CV/h) to a Q-Sepharose-ff column (1.0×10 cm, V=8 ml) from the Pharmacia Biotech Company (Freiburg, GFR) which had been equilibrated with 20 mmol/l Tris-HCl, 50 mmol/l NaCl, pH 7.8 and the column was developed with equilibration buffer while fractionating. The fractions containing rFIXa-EGF2-AP-CD protease were identified by non-reducing and reducing SDS PAGE and activity determination.

b) Activation and Purification of the rFX-EGF2-AP-CD Protease Variant with RVV-X

The protease variant rFX-EGF2-AP-CD was digested at 25° C. at a concentration of 0.5 to 2.0 mg/ml and a protease/substrate ratio of 1:100 to 1:200 in 20 mmol/l Tris-HCl, 50 mmol/l NaCl, 10 mmol/l CaCl₂, pH 7.8. The time course of the enzymatic rFX-EGF2-AP-CD activation was monitored by determining the activity with a chromogenic substrate (see example 13a) until the digestion was completed (plateau, maximum activation). For this purpose samples (10 to 100 μl) were taken from the reaction preparation at intervals of 15-30 min over a period of up to 4 hours and the generated FXa activity was determined. After reaching the activation plateau, the active rFXa-EGF2-AP-CD protease was purified by chromatography on benzamidine-Sepharose-CL-6B.

Only the activated rFXa-EGF2-AP-CD protease variant binds under the given conditions to benzamidine-Sepharose-CL-6B.

The digestion preparation was applied (2 CV/h) to a benzamidine-Sepharose-CL-6B column (1.0×10 cm, V=8 ml; loading capacity: 2-3 mg protein/ml gel) from the Pharmacia Biotech Company (Freiburg, GFR) which had been equilibrated with 20 mmol/l Tris-HCl, 200 mmol/l NaCl, pH 8.0 and washed with the equilibration buffer urtil the absorbance of the eluate at 280 nm reached the blank value of the buffer. The bound material was eluted with 10 mmol/l benzamidine in 20 mmol/l Tris-HCl, 200 mmol/l NaCl, pH 8.0 (2 CV/h). The fractions containing rFXa-EGF2-AP-CD protease were identified by non-reducing and reducing SDS PAGE and activity determination.

c) Activation with RVV-X and Purification of the Chimeric rFIX/X-EGF2-AP-CD Protease Variant

The protease variant rFIX/X-EGF2-AP-CD was digested at 25° C. at a concentration of 0.5 to 2.0 mg/ml and a protease/substrate ratio of 1:10 to 1:20 in 20 mmol/l Tris-HCl, 50 mmol/l NaCl, 10 mmol/l CaCl₂, pH 7.8. The time course of the enzymatic rFIX/X-EGF2-AP-CD activation was monitored by determining the activity with a chromogenic substrate (see example 13a) until the digestion was completed (plateau, maximum activation). For this purpose samples (10 to 100 μl) were taken from the reaction preparation at intervals of 3-4 h over a period of up to 24 hours and the generated rFIX/Xa-EGF2-AP-CD activity was determined. After reaching the activation plateau, the RVV-X digest was purified by negative chromatography on Q-Sepharose-ff.

RVV-X and non-activated rFIX/X-EGF2-AP-CD protease bind under the given conditions to Q-Sepharcse-ff, but the activated rFIX/Xa-EGF2-AP-CD protease variant does not.

The digestion preparation was applied (3 CV/h) to a Q-Sepharose-ff column (1.0×10 cm, V=8 ml) from the Pharmacia Biotech Company (Freiburg, GFR) which had been equilibrated with 20 mmol/l Tris-HCl, 50 mmol/l NaCl, pH 7.8 and the column was developed with equilibration buffer while fractionating. The fractions containing rFIX/Xa-EGF2-AP-CD protease were identified by non-reducing and reducing SDS PAGE and activity determination.

EXAMPLE 13 Characterization of Purified Protease Variants

a) Activity Test

The activity of the renatured activated rFIXa-EGF2-AP-CD, rFXa-EGF2-AP-CD and rFIXa/Xa-EGF2-AP-CD protease variants was determined using the chromogenic substrate Chromozym X (Boehringer Mannheim GmbH, Mannheim, GFR, cat.No. 789763). 10-100 μl sample was made up to 200 μl with 190-100 μl 50 mmol/l Tris-HCl, 150 mmol/l NaCl, 5 mml/l CaCl₂, 0.1% polyethylene glycol 8K (PEG 8000), pH 8.0, admixed with 20 μl Chromozym X (0.5-40 mmol) and measured at a wavelength of 405 nm and RT against a reagent blank value in an ELISA reader. The activity and the kinetic constants were determined from the linear initial slope according to the Michaelis Menten equation.

b) SDS PAGE

Oligomer and aggregate formation by intermolecular disulfide bridge formation as well as the homogeneity and purity of the renatured activated and purified protease variants were examined by non-reducing (minus mercaptoethanol) and reducing (plus mercaptoethanol) SDS PAGE (Laemmli, U K, Nature 227 (1970) 680-685).

EXAMPLE 14 FX Activator Test

The recombinantly produced highly pure inactive rFX-EGF2-AP-CD zymogen (free of any interfering side activity) is for example very suitable for determining low FIXa concentrations in aqueous solutions, preferably in body fluids such as blood or plasma. FIXa activates the inactive rFX-EGF2-AP-CD zymogen by cleavage. The zymogen activation is measured by a coupled indicator region using a chromogenic FXa peptide substrate such as e.g. Chromozym X. The FIXa activity to be determined is amplified by the amplification system of the zymogen activation. Such a FIXa test is for example described by Van Dam-Mieras, M. C. E. et al., In: Bergmeyer, H. U. (ed.), Methods of Enzymatic Analysis, Vol. V, page 365-394, 3rd ed., Academic Press, New York (1983).

Test Principle:

1. FIXa rFX-EGF2-AP-CD → rFXa-EGF2-AP-CD rFXa-EGF2-AP-CD 2. MOC-D-NleGlyArg-pNA → MOC-D-NleGlyArg + pNA Measurement signal: pNA (p-nitroaniline) FXa substrate: MOC-D-NleGlyArg-pNA (Chromozym X) Test mixture: 200 μ1 buffer + 20 μl rFX-EGF2-AP-CD (0.13 mg/ml; 4 μmol/l) + 25 μl substrate (Chromozym X, 8 mmol/l) + 20 μl FIXa sample Buffer: 50 mmol/1 Tris-HCl, pH 8.0, 150 mmol/l NaCl; 5 mol/l CaCl²; 0.1% PEG 8000

The test mixture was incubated at RT in a microtitre plate and the absorbance was measured at 405 nm against a reagent blank value versus time. The direct conversion of Chromozym X by FIXa is negligible under the given test conditions.

The factor IXa catalysed activation of the zymogen rFX-EGF2-AP-CD is measured using the chromogenic peptide substrate Chromozym X. The formation of p-nitroaniline (measurement signal) is a measure (proportional) of the factor IX activity (to be determined) that is present.

EXAMPLE 15 Crystallization of rFXa-EGF2-AP-CD

The activated purified recombinantly produced rFXa-EGF2-AP-CD protease was dialysed for 6 h at 4° C. against 2×100 vol 5 mmol/l HEPES buffer, pH 6.5 and subsequently concentrated to a concentration of 10 mg/ml in a Centrikon® 10 microconcentrator from the Amicon Company (Witten, GFR). It is crystallized by vapour diffusion in a sitting drop. 4 μl concentrated rFXa-EGF2-AP-CD protease (at an equimolar concentration with the inhibitor H-Glu-Gly-Arg-chloromethylketone (Bachem Biochemica, GmbH, Heidelberg, GFR) was admixed at 4° C. with 4 μl 100 mmol/l Tris-HCl, 5 mmol/l CaCl₂, 22% polyethylene glycol 6K (PEG 6K), pH 8.2. and equilibrated at 4° C. against a reservoir of 500 μl 100 mmol/l Tris-HCl, 5 mmol/l CaCl₂, 22% PEG 6K, pH 8.2 by vapour diffusion in a sitting drop. Crystals grew after 3 to 7 days.

EXAMPLE 16 Test for Finding PXa Inhibitors

FXa protease inhibitors were identified by inhibition of the FXa activity. For this the FXa activity of the recombinantly produced rFXa-EGF2-AP-CD protease variants was determined in the absence and presence of the substance to be tested or of a substance mixture and the percentage inhibition was calculated by forming the quotient. The inhibition constant Ki was determined from the inhibition kinetics.

Test Principle:

rFXa-EGF2-AP-CD MOC-D-NleGlyArg-pNA → MOC-D-NleGlyArg + pNA Measurement signal: pNA (p-nitroaniline) FXa substrate: MOC-D-NleGlyArg-pNA (Chromozym X) Test mixture: 200 μ1 buffer + 20 μl rFX-EGF2-AP-CD (0.13 mg/ml; 4 μmol/l) + 25 μl substrate (Chromozym X, 8 mmol/l) + 20 μl FIXa sample Buffer: 50 mmol/1 Tris-HCl, pH 7.4, 150 mmol/l NaCl; 5 mol/l CaCl₂; 0.1% PEG

The test mixture was incubated at RT in a microtitre plate and the linear initial gradient (ΔA/min) was determined by absorbance measurements at 405 nm.

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17 41 base pairs nucleic acid single linear other nucleic acid /desc = “primer” not provided 1 AAAAAAGAAT TCTCATGATC GTGGGAGGCC AGGAATGCAA G 41 41 base pairs nucleic acid single linear other nucleic acid /desc = “primer” not provided 2 AAAAAAAAGC TTCATTACTT GGCCTTGGGC AAGCCCCTGG T 41 77 base pairs nucleic acid single linear other nucleic acid /desc = “primer” not provided 3 AATTCATTAA AGAGGAGAAA TTAAAATGCA TCACCACCAC GACGATGACG ACAAGATCGT 60 GGGAGGCCAG GAATGCA 77 71 base pairs nucleic acid single linear other nucleic acid /desc = “primer” not provided 4 CATTCCTGGC CTCCCACGAT CTTGTCGTCA TCGTCGTGGT GGTGATGCAT TTTAATTTCT 60 CCTCTTTAAT G 71 59 base pairs nucleic acid single linear other nucleic acid /desc = “primer” not provided 5 AAAAAAGAAT TCATTAAAGA GGAGAAATTA AAATGCGGAA GCTCTGCAGC CTGGACAAC 59 58 base pairs nucleic acid single linear other nucleic acid /desc = “primer” not provided 6 AAAAAAGAAT TCATTAAAGA GGAGAAATTA AAATGTGCGG TAAACAGACC CTGGAACG 58 35 base pairs nucleic acid single linear other nucleic acid /desc = “primer” not provided 7 AAAAAACCAT GGTTGCTCAG GCTACCAGCA GCAGC 35 37 base pairs nucleic acid single linear other nucleic acid /desc = “primer” not provided 8 AAAAAACCAT GGTTGTTGGT GGAGAAGATG CCAAACC 37 42 base pairs nucleic acid single linear other nucleic acid /desc = “primer” not provided 9 AAAAAAAAGC TTCATTAAGT GAGCTTTGTT TTTTCCTTAA TC 42 39 base pairs nucleic acid single linear other nucleic acid /desc = “primer” not provided 10 AAAAAACCAT GGATGTAACA TGTAACATTA AGAATGGCA 39 24 base pairs nucleic acid single linear other nucleic acid /desc = “primer” not provided 11 GGGTTCGTCC AGTTCCAGAA GGGC 24 61 base pairs nucleic acid single linear other nucleic acid /desc = “primer” not provided 12 AAAAAAAGGC CTGCATTCCC ACAGGGCCCT ACCCCTGTGG AAGAGTTTCT GTTTCACAAA 60 C 61 42 base pairs nucleic acid single linear other nucleic acid /desc = “primer” not provided 13 AAAAAATCCG GAAGGCAAAT AGGTGTAACG TAGCTGTTTA GC 42 31 base pairs nucleic acid single linear other nucleic acid /desc = “primer” not provided 14 AAAAAATCCG GAGCGTGACT GGGCCGAGTC C 31 1404 base pairs nucleic acid single linear cDNA not provided 15 CTGCTCGGGG AAAGTCTGTT CATCCGCAGG GAGCAGGCCA ACAACATCCT GGCGAGGGTC 60 ACGAGGGCCA ATTCCTTTCT TGAAGAGATG AAGAAAGGAC ACCTCGAAAG AGAGTGCATG 120 GAAGAGACCT GCTCATACGA AGAGGCCCGC GAGGTCTTTG AGGACAGCGA CAAGACGAAT 180 GAATTCTGGA ATAAATACAA AGATGGCGAC CAGTGTGAGA CCAGTCCTTG CCAGAACCAG 240 GGCAAATGTA AAGACGGCCT CGGGGAATAC ACCTGCACCT GTTTAGAAGG ATTCGAAGGC 300 AAAAACTGTG AATTATTCAC ACGGAAGCTC TGCAGCCTGG ACAACGGGGA CTGTGACCAG 360 TTCTGCCACG AGGAACAGAA CTCTGTGGTG TGCTCCTGCG CCCGCGGGTA CACCCTGGCT 420 GACAACGGCA AGGCCTGCAT TCCCACAGGG CCCTACCCCT GTGGGAAACA GACCCTGGAA 480 CGCAGGAAGA GGTCAGTGGC CCAGGCCACC AGCAGCAGCG GGGAGGCCCC TGACAGCATC 540 ACATGGAAGC CATATGATGC AGCCGACCTG GACCCCACCG AGAACCCCTT CGACCTGCTT 600 GACTTCAACC AGACGCAGCC TGAGAGGGGC GACAACAACC TCACCAGGAT CGTGGGAGGC 660 CAGGAATGCA AGGACGGGGA GTGTCCCTGG CAGGCCCTGC TCATCAATGA GGAAAACGAG 720 GGTTTCTGTG GTGGAACCAT TCTGAGCGAG TTCTACATCC TAACGGCAGC CCACTGTCTC 780 TACCAAGCCA AGAGATTCGA AGGGGACCGG AACACGGAGC AGGAGGAGGG CGGTGAGGCG 840 GTGCACGAGG TGGAGGTGGT CATCAAGCAC AACCGGTTCA CAAAGGAGAC CTATGACTTC 900 GACATCGCCG TGCTCCGGCT CAAGACCCCC ATCACCTTCC GCATGAACGT GGCGCCTGCC 960 TGCCTCCCCG AGCGTGACTG GGCCGAGTCC ACGCTGATGA CGCAGAAGAC GGGGATTGTG 1020 AGCGGCTTCG GGCGCACCCA CGAGAAGGGC CGGCAGTCCA CCAGGCTCAA GATGCTGGAG 1080 GTGCCCTACG TGGACCGCAA CAGCTGCAAG CTGTCCAGCA GCTTCATCAT CACCCAGAAC 1140 ATGTTCTGTG CCGGCTACGA CACCAAGCAG GAGGATGCCT GCCAGGGGGA CAGCGGGGGC 1200 CCGCACGTCA CCCGCTTCAA GGACACCTAC TTCGTGACAG GCATCGTCAG CTGGGGAGAG 1260 GGCTGTGCCC GTAAGGGGAA GTACGGGATC TACACCAAGG TCACCGCCTT CCTCAAGTGG 1320 ATCGACAGGT CCATGAAAAC CAGGGGCTTG CCCAAGGCCA AGAGCCATGC CCCGGAGGTC 1380 ATAACGTCCT CTCCATTAAA GTGA 1404 1389 base pairs nucleic acid single linear DNA (genomic) not provided 16 ATGCAGCGCG TGAACATGAT CATGGCAGAA TCACCAGGCC TCATCACCAT CTGCCTTTTA 60 GGATATCTAC TCAGTGCTGA ATGTACAGTT TTTCTTGATC ATGAAAACGC CAACAAAATT 120 CTGAATCGGC CAAAGAGGTA TAATTCAGGT AAATTGGAAG AGTTTGTTCA AGGGAACCTT 180 GAGAGAGAAT GTATGGAAGA AAAGTGTAGT TTTGAAGAAG CACGAGAAGT TTTTGAAAAC 240 ACTGAAAGAA CAACTGAATT TTGGAAGCAG TATGTTGATG GAGATCAGTG TGAGTCCAAT 300 CCATGTTTAA ATGGCGGCAG TTGCAAGGAT GACATTAATT CCTATGAATG TTGGTGTCCC 360 TTTGGATTTG AAGGAAAGAA CTGTGAATTA GATGTAACAT GTAACATTAA GAATGGCAGA 420 TGCGAGCAGT TTTGTAAAAA TAGTGCTGAT AACAAGGTGG TTTGCTCCTG TACTGAGGGA 480 TATCGACTTG CAGAAAACCA GAAGTCCTGT GAACCAGCAG TGCCATTTCC ATGTGGAAGA 540 GTTTCTGTTT CACAAACTTC TAAGCTCACC CGTGCTGAGA CTGTTTTTCC TGATGTGGAC 600 TATGTAAATT CTACTGAAGC TGAAACCATT TTGGATAACA TCACTCAAAG CACCCAATCA 660 TTTAATGACT TCACTCGGGT TGTTGGTGGA GAAGATGCCA AACCAGGTCA ATTCCCTTGG 720 CAGGTTGTTT TGAATGGTAA AGTTGATGCA TTCTGTGGAG GCTCTATCGT TAATGAAAAA 780 TGGATTGTAA CTGCTGCCCA CTGTGTTGAA ACTGGTGTTA AAATTACAGT TGTCGCAGGT 840 GAACATAATA TTGAGGAGAC AGAACATACA GAGCAAAAGC GAAATGTGAT TCGAATTATT 900 CCTCACCACA ACTACAATGC AGCTATTAAT AAGTACAACC ATGACATTGC CCTTCTGGAA 960 CTGGACGAAC CCTTAGTGCT AAACAGCTAC GTTACACCTA TTTGCATTGC TGACAAGGAA 1020 TACACGAACA TCTTCCTCAA ATTTGGATCT GGCTATGTAA GTGGCTGGGG AAGAGTCTTC 1080 CACAAAGGGA GATCAGCTTT AGTTCTTCAG TACCTTAGAG TTCCACTTGT TGACCGAGCC 1140 ACATGTCTTC GATCTACAAA GTTCACCATC TATAACAACA TGTTCTGTGC TGGCTTCCAT 1200 GAAGGAGGTA GAGATTCATG TCAAGGAGAT AGTGGGGGAC CCCATGTTAC TGAAGTGGAA 1260 GGGACCAGTT TCTTAACTGG AATTATTAGC TGGGGTGAAG AGTGTGCAAT GAAAGGCAAA 1320 TATGGAATAT ATACCAAGGT ATCCCGGTAT GTCAACTGGA TTAAGGAAAA AACAAAGCTC 1380 ACTTAATGA 1389 10 amino acids amino acid single linear peptide not provided 17 Met His His His His Asp Asp Asp Asp Lys 1 5 10 

What is claimed is:
 1. An isolated, non-glycosylated, enzymatically active protein with serine protease activity or a zymogenic form thereof consisting of the following domains of a member of the factor IX family: (a) at least one of either an EGF1 or EGF2 domain, linked by its C-teiminus to, (b) the N-teiminus of a zymogen activation domain, which is linked by its C-teirminus to, (c) the N-teiminus of a catalytic domain.
 2. The isolated protein of claim 1, wherein (a) is an EGF1 domain.
 3. The isolated protein of claim 1, wherein (a) is an EGF2 domain.
 4. The isolated protein of claim 1, wherein (a) consists of an EGF 1 domain linked by its C-terminus to the N-teiminus of an EGF2 domain.
 5. The isolated protein of claim 1 wherein at least one of (a), (b), and (c), is from a member of the factor IX family which differs from the family from which the other domains are from.
 6. The isolated protein of claim 1, wherein each of (a), (b), and (c) is from a different member of the factor IX family.
 7. The isolated protein of claim 1, wherein said EGF2 domain and said catalytic domain are from factor X, and said zymogen activation domain is from factor IX.
 8. The isolated protein of claim 1 wherein (a), (b), and (c), are from either factor IX or factor X.
 9. The isolated protein of claim 8, wherein at least one of (a), (b), and (c) is from factor IX, and the remaining domains are from factor X.
 10. The isolated protein of claim 8, wherein at least one of (a), (b), and (c) is from factor X, and the remaining domains are from factor IX.
 11. A process for the manufacture of the protein of claim 1, comprising transforming a prokaryotic cell with an expression vector that encodes said protein and culturing the transfoimed prokaiyotic cell under conditions favoring production of said protein.
 12. A method for determining if a substance is an inhibitor or activator of a member of the factor IX family, comprising contacting said substance with the isolated protein of claim 1, and determining activity of said protein, wherein a change in said activity, relative to said activity prior to said contact is indicative of activator or inhibitor properties of said substance.
 13. A method for the determination of factor IXa in a sample comprising incubating a zymogenic form of the protein of claim 1 with a substrate cleavable by an active form of said zymogen, wherein determining cleavage of said substrate is indicative of factor IXa in a sample.
 14. The method of claim 13, wherein said sample is a body fluid.
 15. The method of claim 13, wherein said cleavable substrate is a chromogenic substrate.
 16. The method of claim 13, wherein the cleavable substrate is a second zymogenic form of an enzyme activatable by the active form of the protein of claim 1, which is activatable by the factor IXa.
 17. An isolated, non-glycosylated, enzymatically active protein with serine protease activity or a zymogenic form thereof, consisting of an amino acid sequence encoded by nucleotides 322 to 462 of SEQ ID NO: 15, concatenated to an amino acid sequence encoded by nucleotides 535 to 1005 of the nucleotide sequence set forth in SEQ ID NO: 16, concatenated to an amino acid sequence encoded by nucleotides 964 to 1362 as set forth in SEQ ID NO:
 15. 